PHP How to sort an array by value while retaining the original key names?

PHP provides two ways to sort associative arrays by value: Use the asort() function: sort the values ​​from small to large while retaining the original key names. Using the usort() function and closures: Sort values ​​by a custom comparison function while preserving the original key names.

Using the asort() function

PHP’s asort() function Associative arrays can be sorted by value while preserving the original key names. It accepts an associative array as argument and sorts the values ​​from smallest to largest.

<?php
$arr = [
    "apple" => 5,
    "banana" => 3,
    "orange" => 2,
    "grape" => 4,
];

asort($arr);

print_r($arr);
?>

Output:

Array
(
    [orange] => 2
    [banana] => 3
    [grape] => 4
    [apple] => 5
)

As you can see, the values ​​of the array have been sorted from small to large, but the key names remain unchanged.

Using usort() Functions and closures

Another way is to use usort() Functions and closures Bag. usort() Accepts a callback function as a parameter, which is used to compare elements in the array. A closure is an anonymous function that can be used as a callback.

<?php
$arr = [
    "apple" => 5,
    "banana" => 3,
    "orange" => 2,
    "grape" => 4,
];

usort($arr, function ($a, $b) {
    return $a[1] - $b[1];
});

print_r($arr);
?>

Output:

Array
(
    [orange] => 2
    [banana] => 3
    [grape] => 4
    [apple] => 5
)

In this case, the closure compares the value of each element ($a[1] and $b[ 1]), and returns -1, 0, or 1, depending on which value is greater.

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